1. Field of the Invention
The present invention relates to an illumination apparatus and a projection type image display apparatus using it.
2. Description of the Related Art
In recent years, liquid crystal projectors have become popular for many uses because they fulfill user's desires for a large area display in applications such as a personal computer or a television, and improvements in the technology relating to liquid crystals have made it easier to manufacture a large area display.
Although the liquid crystal projector and a CRT (Cathode-Ray Tube) projector have similar functions, the former provides better image quality and is smaller and lighter than the latter. However, conventional liquid crystal projectors do not provide a sufficiently bright screen, and an improvement in brightness is now desired in many applications. It is common to use a combination of a high-luminance lamp and a paraboloidal or a ellipsoidal reflector as a light source to improve brightness. However, the generated light beam is poor in illuminance uniformity. Therefore it is necessary to improve the uniformity of the screen luminance.